Contamination of whole blood or blood products with infectious microorganisms such as HIV, hepatitis and other viruses and bacteria present a serious health hazard for those who must receive transfusions of whole blood or administration of various blood products or blood components such as platelets, red cells, blood plasma, Factor VIII, plasminogen, fibronectin, anti-thrombin III, cryoprecipitate, human plasma protein fraction, albumin, immune serum globulin, prothrombin complex plasma growth hormones, and other components isolated from blood. Blood screening procedures may miss pathogenic contaminants, and sterilization procedures which do not damage cellular blood components but effectively inactivate all infectious viruses and other microorganisms have not heretofore been available.
In some circumstances, certain blood components may themselves be harmful to the desired blood product. For example, white blood cells, which are part of the donor's immune system, may cause an adverse reaction in the recipient of a red blood cell product. Many white cells are separated by centrifugation from the desired red blood cells, but some usually remain mixed with the red blood cells. The undesired white blood cells may be considered a “contaminant” or “pathogen” with respect to the desired relatively pure red blood cell product. The white blood cells may be inactivated in the same manner as an infectious virus or microorganism.
The use of pathogen inactivating agents include certain photo sensitizers, or compounds which absorb light of defined wavelengths and transfer the absorbed energy to an energy acceptor, have been proposed for inactivation of microorganisms found in blood products or fluids containing blood products. Such photo sensitizers may be added to the fluid containing blood or blood products and irradiated.
The photo sensitizers which may be used in this invention include any photo sensitizers known to the art to be useful for inactivating microorganisms. A “photo sensitizer” is defined as any compound which absorbs radiation at one or more defined wavelengths and subsequently utilizes the absorbed energy to carry out a chemical process. Examples of photo sensitizers which may be used for the reduction of pathogens in blood or blood products include porphyrins, psoralens, dyes such as neutral red, methylene blue, acridine, toluidines, flavine (acriflavine hydrochloride) and phenothiazine derivatives, coumarins, quinolones, quinones, and anthroquinones.
A number of systems and methods for irradiating pathogens in a fluid with light either with or without the addition of a photo sensitizer are known in the art. For example, U.S. Pat. No. 5,762,867 is directed toward a system for activating a photoactive agent present in a body fluid with light emitting diodes (LEDs).
U.S. Pat. No. 5,527,704 is directed toward an apparatus containing LEDs used to activate a fluid containing methylene blue.
U.S. Pat. No. 5,868,695 discloses using LEDs having a red color and emitting light at a wavelength of 690 nm in combination with benzoporphrin derivative photo sensitizers to inactivate red blood cells. As taught in this patent, at a wavelength of 690 nm, red blood cells are essentially transparent to radiation, and as such, the benzoporphorin derivatives absorb radiation at this wavelength to become activated. Also disclosed in this patent is the use of LEDs having a blue color and emitting light at a peak wavelength of 425 mn to inactivate platelets.
U.S. Pat. No. 5,658,722 discloses irradiating platelets using UVA1 light having an emission peak near 365 nm. This patent teaches that damage to platelets is caused by short UVA<345 nm, and unlike the present invention, calls for removing UVA wavelengths below 345 nm.
Use of light which is variably pulsed at a wavelength of 308 nm without the addition of a photo sensitizer to inactivate virus in a washed platelet product is taught in an article by Prodouz et al. (Use of Laser-UV for Inactivation of Virus in Blood Products; Kristina Prodouz, Joseph Fratantoni, Elizabeth Boone and Robert Bonner; Blood, Vol 70, No. 2). This article does not teach or suggest the addition of a photo sensitizer in combination with light to kill viruses.
U.S. Pat. No. 6,843,961 is directed toward the reduction of pathogens which may be present in blood or blood products using light having peak wavelengths in combination with an endogenous photo sensitizer.
Whether or not a photo sensitizer is used, it is important that the dosage of radiation delivered to the blood or blood component be accurately controlled. Proper calibration of the irradiation apparatus is, therefore, necessary.